Age-resisting rubber compound and method of making the same



Patented Pa." 23, 1926.

UNITED STATES PATENT OFFICE.

' nvnnnrr w. FULLER,

' RUBBER courm, massacnusnrrs.

F SRINGFIELD, MASSACHUSETTS, ASSIGNOR TO THE FISK OF CHICOPEE FALLS, MASSACHUSETTS, A CORPORATION OF AGE-BESISTIH G RUBBER COMPOUND AND METHOD OF MAKING THE SAME.

I Fobrawing.

To all whom it may concern:

4 Beit known that I, EVERETT NV. FULLER, acitizen of the United States of America, residing at Springfield, in the county of 5 Hampden and State of -Massachusetts, have invented certain new and'useful Improvements in an Age-Resisting Rubber Gompound and Method of Making the Same, of

hyde amines, havebeen proposed for use as Q age-resistors in rubber compounds. Such substances, when the do improve the ageing properties of mi ber compounds, serve otherwisevno useful purpose and their use means an added expense for this purpose 5 alone. I v g I have found, however, that certain nitroso compounds of the aromatic series have in a marked degree the property of imparting good ageing qualities to rubber mixtures when incorporated therein with an organic accelerator and a vulcanizing agent such as sulphur, and at the same time they assist the acceleration of vulcanization so that less of the organic accelerator is needed to efiect a cure in a given time. These nitroso compounds, therefore, serve the double purpose of age-resistors and accelerators. In partic-ular I have found useful in this connection the metallic salts of alpha-nitroso-betanaphthol, such as the sodium salt. These compounds probably have the structural formulae NOM stable, and have considerable effect as ageimprovers whileat the same time assisting in the acceleration of the cure.

Application filed April 27, 1925. Serial No. 26,300.

To illustrate the manner of use and theeffeet such nitroso compounds have on the ageing properties and cure of rubber mixtures, the following examples are given. Type formulae for the rubber mixture are chosen, accelerated by the well-known diortho tolyl-guanidine and the polymerization product of ethylidene aniline respectively. The desired effect maybe produced, however, in rubber mixtures of other composition and accelerated by other organic accelerators, and the'age-improving and accelerating characteristics of these nitroso compounds are not limited to the specific rubber mixture given. 4

Example [.The following rubber mix tures were prepared, quantities being expressed 1n grams. 4

Test slabs were cured in a press for 30 minutes at 50 pounds steam pressure. The cured slabs were given the accelerated a eing test that is generally used for determ1ning the ageing properties of rubber mixturcs, and that has been described by W. W Evans in the Proceedings of the American Society for Testing Materials, vol. 22, Part II, page 549 (1922). The tensileat break and elongation at break at the start indicate the relative states of cure of the above mixtures, while the tensile at break after 15 days accelerated ageing indicate the ageresisting properties of the mixtures. To bring out more clearly the latter point, the

final tensile is also given. in percent of the original tensile.

Original. i5 days ageing.

. elonof ori Tensile. Z Tensile. g

I MixtureA 2790 0.00 1500 54 MixtureB 3210 5.85 1950 so Mixture c 3330 5.90 2340 70 Mixture D 3000 5.80 2170 j 72 The increase in original tensiles and relative decrease in, elongations indicate that the addition of the above age-resistors has increased the acceleration of cure above that of mixture A, with the lesser amount of diortho-tolyl-guanidine, and nearly or actually equal to that of mixture B with the larger amount of organic accelerator. The higher final tensiles after ageing show the improvement in ageing properties secured by the use of these age-resistors.

- Example H.These age-resistors are also effective in those types of compounds having a low zinc oxide content, as shown in the following examples.

E. F o. H. I

Rubber 100 100 100 100 100 Zinc oxide 6 6 6 6 6 Sulphur 3% 3% 3% 3% 3% Di-ortho-tolyl-guanidine 24 96 Sodium salt of nitroso-fi-mnhfhnl Potassium salt nitroso-B-nanhthnl 1 Calcium salt nitroso-B-naphthol...

Test slabs were cured 30 minutes at 50 pounds steam pressure in a press and were given the accelerated ageingtest as in ExampleI.

Original. 15 days ageing.

7 elonof orig- Tensile. 3 Tensile. inal.

2430 6. 90 1070 44 3200 6. 60 1300 41 2940 6. 40 2030 69 3170 6.50 2200 69 Mixture I 3200 6. 40 2140 67 Again the increase in original tensile with corresponding decrease in elongation indicate the accelerating action of the age-resistors, while the final tensiles after 15 days ageing show the improvement in ageing properties of the mixtures containing these compounds.

E wample III.The eflect oi the addition of oneof these age-resistorsto a mixture accelerated with the polymerization product of ethylidene aniline is shown by the followingv results.

Rubber 100 100 Zinc oxide 100 100 Sulphur 3 v 3 Polymerization product of ethylidene aniline Sodium salt nltroso-fi-naphthol 1 Test slabs were cured 45 minutes at '50 pounds steam in a press and were given the above described ageing test for 11 days.

Original. 11 days ageing.

7 elonoi orig- Tensile. 3 Tensile.

li'wample IVE-In the following case the addition of the age-resistor has allowed the amount of'orgamc accelerator to be cut to.

one half that used in the control While the ageing properties of the mixture are improved.

Rubber 100 100 Zinc Oxide 6 6 Sulphur 3A 3% Polymerization product of ethylidene aniline 1 y Sodium salt nitroso-fi-nanhthzfl 1 Test slabs were cured 45 minutes at 35 pounds steam pressure in a press and were given the above described ageing testfor 17 days.

Original.

17 deysf ageing.

- 7 elon- 4 7 of orig- Tensile. Tensile. ainaL Mixture L 2700 7. 60 1560 58 Mixture M 2690 7. 50 2490 92 derivatives of nitroso-beta-naphthol mentioned, as both mixture and added nitrosobeta-naphthol derivative may be varied in character and amount from the above exam les. Certain of the nitroso-beta-naphtho derivatives may function more satisfactorily in some mixtures than in others, but

. the examples iven are sufficient to instruct those skilled in the .art in the'use of this invention without namin the optimum conditions for all variations in its use.

Having thus described my invention, I claim:

1. A method of making rubber products having improved ageing qualities which comprises adding an alkali or alkaline earth salt of alpha-nitroso-beta-naphthol to a vul canizable rubber compound and vulcanizing the mixture.

2. A. method of making rubber products having improved ageing qualities .which comprises adding an alkali or alkaline earth salt of alpha-nitroso-beta-naphthol to a vulcanizable rubber compound containing a subnormal quantity of an organic accelerator and 'vulcanizing the mixture. action product of rubber, sulphur, zinc ox- 3. A method of making rubber products ide, an organic accelerator, and an alkali or having improved ageing qualities which alkaline earth salt of alpha-nitroso-beta- 15 comprises adding a small quantity of the naphthol. F sodium salt of alpha-nitroso-beta-naphthol 6. Vulcanized rubber containing the reacto a vulcanizable rubber compound and vultion product of rubber, sul bur, and the socanizing the mixture. f dium salt of alpha-nitrosoeta-naphthol.

4. Vulcanized rubber containing the re- 7. Vulcanized rubber containing the reactionproduct of rubber, sulphur, and an action product of rubber, sulphur, zinc ox- 9 alkali or alkaline earth [salt of alpha-ni ide, an organic accelerator, and the sodium T troso-beta-naphthol. salt of alpha-nitroso-beta-naphthol.

5. Vulcanized rubber containing the re- EVERETT W. FULLER. 

